Determinants of Wait Time for Autism Spectrum Disorder Diagnostic Assessment in Canada

Background:   The increasing prevalence of autism spectrum disorder (ASD) diagnoses and a shortage of skilled practitioners have contributed to substantial wait times for diagnostic assessment. These wait times occur during an important window for social learning and may result in suboptimal developmental outcomes. Identifying factors related to provider characteristics and assessment practices may help to streamline the assessment process, reducing wait times.

Objectives: The objective of this study was to identify determinants of wait times for ASD diagnostic assessment in Canada.

Methods:  An online national survey was conducted through the Canadian Paediatric Society’s Developmental Paediatrics, Community Paediatrics, and Mental Health sections, which were identified as the groups of pediatricians most likely to encounter children with suspected ASD. Participants were asked for demographic information and whether they diagnosed ASD. Those who diagnosed ASD were asked about the elements of their assessment, duration of assessment, and wait times. A linear regression was performed using natural log transformed total wait time (time from referral to communication of the diagnosis to the family) as the dependent variable. Hypothesized explanatory variables included assessment duration, type of assessor (general pediatrician, developmental pediatrician, other), use of a multi-disciplinary team, accepting referrals from primary care physicians, catchment area, province of practice, and number of years in practice. 

Results:  The overall response rate for the survey was 14% (91 completed surveys out of 639 individuals solicited). Fifty-seven participants indicated that they diagnosed ASD in their practice (62.6%) and were included in the analysis. This sample was 66% female (n=38, versus 19 males) with a median age of 52 (range 29 to 77). The median reported total wait time was 208 days (interquartile range 119, 365). Bivariate analyses for total wait time identified assessment duration (Spearman r = 0.31, p = 0.02), type of assessor (Kruskal Wallis chi-squared = 3.66, p = 0.16), and province (Kruskal Wallis chi-squared = 13.67, p = 0.19) as potential explanatory variables. Assessment duration was significantly associated with type of assessor (Kruskal Wallis chi-squared = 5.59, p = 0.003) so these variables were not tested together in the model. Assessment duration was the only variable that remained significant when tested in the regression model (p = 0.002) and accounted for 15% of the variance in the model. The back-transformed mean adjusted total wait time was 254 days (95% confidence interval 214, 302). 

Conclusions:  Canadian wait times for ASD diagnostic assessment are substantial, encompassing over eight months from referral to communication of the diagnosis to families. The amount of time spent on the assessment is a significant determinant of wait time, highlighting the need for efficient assessment practices.